Date: Mon, 29 Mar 2021 15:26:17 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 254639] Fork syscall performance Message-ID: <bug-254639-227-pG9prDzKe7@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-254639-227@https.bugs.freebsd.org/bugzilla/> References: <bug-254639-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254639 Mark Johnston <markj@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |markj@FreeBSD.org --- Comment #1 from Mark Johnston <markj@FreeBSD.org> --- How much RAM do you have? Hopefully more than 100GB. I suspect that we're spending a lot of time in pmap_copy(), which copies pa= ge tables into the child process. It only copies referenced PTEs, but in this case we'll copy all of the page tables backing some_str. You can try something like this to confirm: # dtrace -q -n 'fbt::pmap_copy:entry /pid =3D=3D $target/{self->ts =3D time= stamp} fbt::pmap_copy:return /self->ts/{@ =3D sum(timestamp - self->ts); self->ts = =3D 0;} tick-1s {printa("spent %@dns copying\n", @); clear(@);}' -c "python test.py" --=20 You are receiving this mail because: You are the assignee for the bug.=
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